Patent GB-201177-A (GB)
Title: Improvements in or relating to means for the coupling of alternating current dynamo-electric machines in parallel
IPC: H02J3/42
Filed: 1923-07-20
Abstract: 201,177. Metropolitan - Vickers Electrical Co., Ltd., (Assignees of Bradshaw, W. M., and Ashbaugh, H.). July 20, 1922, [Convention date]. Regulation, automatic appara. tus for; systems depending on the use of two or more machines.-An alternator is connected up automatically to the bus-bar of another alternator by means operated in accordance with the speed of the incoming alternator, the phase relationship of the alternators, and the voltages of the alternators, and means are provided to control automatically the frequency of the incoming alternator to correspond with that of the bus-bars. An alternator 6, driven by a prime-mover 87, is connected up to the bus-bars 2, 3, 4 of an alternator 1 by means of a switch 57 the operating-coil 56 of which is controlled by a synchronizer 35 and by a voltage relay 60. The speed of the prime-mover 87 is controlled by a governor 8 the setting of which is controlled by a motor 13 controlled by relays 15, 16. Each relay is provided with a permanently energized holding coil 18, an operating coil 19 and a neutralizing coil 21. The relays normally occupy the positions shown under which conditions the motor 13 is short-circuited. The relays 15, 16 are controlled by a differential switch comprising contacts 33, 34 mounted on a lever 80, and a contact 32 operated by the wheel 27 of a differential mechanism 24. The lever 80 is controlled by a spring and an electromagnet 82 comprising two differentially wound coils 83, 84 and a polarizing coil 86. The coils 83, 84 are connected across the armature of the motor 13 and cause the lever 80 to move in one direction or the other in order that the circuit of the motor 13 may be broken earlier than it normally would be and so prevent hunting. The elements 25, 26 of the differential mechanism 24 are driven by synchronous motors 28, 29 supplied with currents from the alternator 1 and 6 respectively and under the control of an automatic or manual switch 31. The synchronizer 35 comprises a pair of solenoids 36, 37 the cores of which are pivoted to a lever 38, a segment 39 mounted on the same pivot as the lever 38 and carrying a contact strip 41, a forked member 47 engaging a pin on the segment 39 and operated through a dash-pot 44, and levers 45, 46 by the lever 38, a contact 42 on the lever 38 and a fixed contact 43. The solenoids 36, 37 are energized by a transformer 49 and transformers 51, 52 in such a manner that when the frequency of the current delivered by the alternator 6 is approximately the same as that of the alternator 1, the pull exerted by the solenoid 37 is grea:er than that exerted by the solenoid 36 and the brush 42 engages the strip 41 to energize the operating coil 56. If the approach to synchronism be slow, the dash-pot connection 44 will prevent the movement of the segment 39. If, however, the approach be rapid, the segment 39 is moved to cause an earlier engagement of the contact 42 and the strip 41. To prevent the operation of the switch 57 when the voltages of the alternators 1 and 6 differ, the operating-coil 56 is short-circuited when either of two relays 68, 69 are closed. The relays 68, 69 are controlled by a differential voltage relay 60 provided with means for preventing hunting of a motor 21 operating a rheostat-arm 72 controlling the energization of the alternator 6.